The invention pertains to high voltage ignition cable connectors. More particularly, the invention relates to moisture proof connectors for igniter leads for aircraft jet engines.
Various types of high voltage ignition cable connectors and igniter leads have been developed for use in aircraft engines. U.S. Pat. No. 2,114,750 issued to Stone is directed to a radio shielding spark plug connection. The spark plug connection has an outer casing that is brazed to a metallic block that is threaded to receive a nut for forming a liquid tight joint with the ignition wire. The metallic casing is closed at its other end with a side opening adapted to connect with stainless steel cylindrical tube. Casing and tube are secured together at an angle in a suitable manner as by brazing.
U.S. Pat. No. 3,146,301 issued to Logan, is directed to a spark discharge device of the angle type. The spark discharge device has a horizontal connector portion that is covered by a shell. The spark discharge device has a vertical spark gap portion that is covered by a metallic shell. The leg portions are so formed as to meet at an annular junction lying in a plane at degrees with respect to the axis of the legs. With the insulator portion installed, the legs are assembled in a fixture and welded as by welding along the outer surfaces at junction.
U.S. Pat. No. 2,399,402, issued to Spengler is directed to an angular electrical connecting and radio shielding means for coupling a flexible metallic high-tension lead to a spark plug. A pair of cooperating cup-shaped metallic members have matching external flanges that can be positioned in a desired acute angle and soldered or brazed together so that the outlets are in a position suitable for the application.
U.S. Pat. No. 2,463,924 issued to Van Orden describes a shielded right angle spark plug lead. The metal shell body of the spark plug shield comprises a shell body sealed by a dome-shaped structure that is integral. The lower portion of the shell is open and expanded into a hollow hexagonal shape, dimensioned to slide snugly over the hexagonal member of a typical aviation spark plug. An outlet is attached as by soldering to the shell for shielding the opening and it provides an external thread at its end for attachment of a shielded conduit.
U.S. Pat. No. 2,398,359 issued to Curtiss discloses a shielded elbow shell spark plug connector. The spark plug connector has one end connected to an aviation spark plug and the other end connected to an electrical conductor. The connector has a hollow metal elbow or shell that is formed of two complementary pressed sheet metal shell halves brazed together and having a union brazed to end and a retainer is brazed to the spark plug connection arm. The completed metal elbow shell is placed in a die with an electrical conductor or cable connector insert held in spaced relation for a molding operation of plastic insulating material that is forced inside.
While other variations exist, the above-described designs for high voltage ignition cable connectors and igniter leads are typical of those encountered in the prior art. It is an objective of the present invention to provide a securely fastenable jet engine igniter lead elbow assembly that provides superior shielding for radio-frequency signals from high voltage ignition noise. It is a further objective to provide such shielding in an elbow assembly that provides complete sealing against moisture and dirt found in the aviation environment. It is yet a further objective to provide an elbow assembly that may be easily disassembled and reassembled for maintenance purposes without damage to the assembly or the igniter components. It is an additional objective of the invention that the elbow assembly may be easily fabricated from standard and readily available components without resort to tubing bending facilities. It is a final further objective of the invention to provide the above-described capabilities in an inexpensive and durable connector that is capable of extended duty cycles.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found include all of the requirements identified.
The present invention addresses all of the deficiencies of prior art jet engine igniter lead elbow assembly inventions and satisfies all of the objectives described above.
A jet engine igniter lead elbow assembly of the present invention may be constructed from the following components. A saddle adapter is provided. The saddle adapter has a horizontal axis, a cylindrical cross-section of a first predetermined diameter about the horizontal axis, a first end and a second end. A first orifice is provided. The first orifice extends from the first end of the saddle adapter to the second end. A semi-circular cutout is provided. The cutout is located at the first end perpendicular to the horizontal axis. The cutout has a first predetermined radius.
A master cylinder is provided. The master cylinder has a vertical axis and a cylindrical cross-section of the first predetermined diameter about the vertical axis. The master cylinder has an outer surface, a closed lower end, an upper end and a second orifice extending from the closed lower end to the upper end. A circular opening is provided. The circular opening is perpendicular to the vertical axis. The circular opening is located adjacent the closed end lower end of the master cylinder and penetrates the outer surface and extends to the second orifice. A first necked down section is provided. The first necked down section is located at the upper end of the master cylinder and has a second predetermined diameter less that the first predetermined diameter. The first necked down section extends from the upper end toward the lower end for a first predetermined distance. The saddle adapter is removably attached to the master cylinder such that the semi-circular cutout is disposed over the circular opening in the master cylinder with the first orifice adjoining the second orifice.
An extension tube is provided. The extension tube has a vertical axis, a cylindrical cross-section of the first predetermined diameter about the vertical axis, a top end, a bottom end and a third orifice extending from the bottom end to the top end. The bottom end has a first counter bore. The first counter bore is sized and shaped to fit slidably over the first necked down section of the master cylinder. The top end has a second necked down section. The second necked down section has the second predetermined diameter and extends from the top end toward the bottom end for the first predetermined distance.
A ferrule is provided. The ferrule has a vertical axis, a cylindrical cross-section, a first end, a second end and a first portion adjacent the first end of the first predetermined diameter about the vertical axis. A second counter bore is provided. The second counter bore is located at the first end of the ferrule and is sized and shaped to fit slidably over the second necked down section of the extension tube. A restraining lip is provided. The restraining lip is located at the second end of the ferrule and has a third predetermined diameter that is greater than the first predetermined diameter. The ferrule is removably attached at its first end to the top end of the extension tube with the second counter bore fitted slidably over the second necked down section.
A nut extension tube is provided. The nut extension tube has a vertical axis, an outer surface, a first end, a second end and a hollow cylindrical body disposed about the vertical axis. The hollow body has an internal diameter greater than the first predetermined diameter and smaller than the third predetermined diameter. A gripping surface is located at the first end of the nut extension tube and a threaded receiving section is located at the second end. The threaded receiving section is sized and shaped to fit slidably over the ferrule and the thread is sized and shaped to accommodate a fitting on a jet engine.
The nut extension tube is fitted over the extension tube and the ferrule. The top end of the extension tube is removably attached to the master cylinder with the first counter bore fitted slidably over the first necked down section. When the extension tube is removably attached to the master cylinder, the nut extension tube will be slidably and rotably held in place by the ferrule.
In a variant of the invention, the saddle adapter includes a third necked down section. The third necked down section is located at the second end of the saddle adapter and has the second predetermined diameter. The third necked down section extends from the second end of the saddle adapter toward the first end for the first predetermined distance.
In another variant, the saddle adapter is removaby attached to the master cylinder using a method selected from silver soldering and the application of high-strength adhesive.
In still another variant, the extension tube is removaby attached to the ferrule and to the master cylinder using a method selected from silver soldering and the application of high-strength adhesive.
In yet another variant of the invention, the gripping surface includes flattened portions sized, shaped and located so that the nut extension tube may be turned using an open end wrench.
In another variant, the nut extension tube further includes annular rings for handling the nut extension tube.
In a final variant of the invention, the assembly is for use with a Pratt and Whitney JT8D jet aircraft engine.